Collagen is used as an implant material to replace or augment hard or soft connective tissue, such as skin, tendons, cartilage, and bone. Some implants are formed as solid, flexible, or deformable collagen masses cross-linked with chemical agents, radiation, or other means to improve mechanical properties, decrease the chance of an immunogenic response, and/or to manage the resorption rate.
Collagen used in medical implants for implantation in humans generally has been of a nonhuman origin, i.e., xenogenic. A problem with the use of xenogenic tissue as a starting material when generating medical implants is that the tissue may be contaminated with viruses or prions. For example, products using bovine sourced tissue have the potential for transmitting BSE (Bovine Spongiform Encephelothopoly). As a result, xenogenic tissue is subjected to one or more processes intended to remove prions or other harmful contaminants. For example, treatment of collagen with an alkali solution has been used to remove harmful and undesirable contaminants from collagen. However, subjecting collagen to an alkali environment is harsh on the collagen tissue and can tend to unnecessarily degrade it.
Another problem with the use of xenogenic tissue is the potential for inflammation responses, hematomas, adhesions, and rejection after implantation. This is because xenogenic collagen includes constituents, such as telo-peptides, that can initiate an immunogenic response in humans. Processing methods for removing telo-peptides from collagen may help in product acceptance into the body. However, even with the removal of the telo-peptides, the implant may be reacted to (i.e., inflammation) and/or rejected due to the xenogenic nature of the collagen or due to irregular or damaged forms of proteins or other materials being revealed that are not recognized by the implantee's biochemistry. Further, processing methods effective in removing telo-peptides or other immunogenic-inducing portions of collagen may degrade the collagen, including by stripping away other portions of the collagen capable of providing potential benefits.
Thus, there is a need for methods for processing collagen, including human collagen, that avoid risks of contamination or infection with foreign pathogens. There also is a need for methods for processing collagen, including human collagen, that addresses constituents that can cause an immunogenic response in humans. There also is a need for methods for processing collagen, including human collagen, that avoid excessive degradation of the collagen. There further is a need for medical products made from the collagen processed by these methods.